Much
to the delight of mule-racing enthusiasts throughout the world, Idaho
Gem, the first mule ever cloned, was born on May 4, 2003, in Moscow, Idaho.
At twelve minutes of age, the mule stood up and started to buck as he
was still being dried off.

“He’s got personality,” says Gordon L. Woods of the
University of Idaho, who led the cloning project. “When he was 33-hours
old, he darted around on the grass like a little rabbit. He hasn’t
missed a beat since.”

Idaho Gem was cloned from the brother of a world-champion racing mule.
Mules are sterile and unable to pass on their genes, but cloning offers
a means of propagating promising bloodlines.

The birth of Idaho Gem grew out of attempts to understand horse fertility.
Despite the success of in vitro fertilization in humans, cattle,
and other species, only two foals have ever been born as a result of the
technique. Attempts to clone horses have also met with failure.

While trying to understand the cloning problems, Woods noticed that many
horse cells have less calcium than normal. Because calcium regulates many
cell activities, he and his colleagues decided to increase the calcium
in eggs for cloning.

As the horse project was getting underway, Don Jacklin, president of
the American Mule Racing Association, offered funding on the condition
that the researchers first clone a mule.

“We wanted to do something no one else had done,” says Jacklin.
“And for the first equine clone, we didn’t want to create
a monster that would overpopulate the world. That’s not a problem
with a sterile hybrid.”

Mules result from the breeding of a male donkey with a female horse.
Donkeys have 62 chromosomes, horses have 64, and mules have 63. Mules
are sterile because their chromosomes cannot pair up evenly, and as a
result they do not produce eggs and sperm.

To create Idaho Gem, the researchers used fetal cells from a brother
of Taz, the champion racer owned by Jacklin. In a process known as nuclear
transfer, they inserted the mule DNA into a horse egg cell that contained
no genetic material. The resulting cloned embryo was transplanted into
the uterus of a surrogate mare.

Black Ruby edges out Taz in a recent mule race in California. Photos by Vassar Photography

The project is reported today online in Science. Two other cloning
attempts have been successful, and the mules are expected be born this
summer.

The researchers are now trying to clone a horse using the same strategy.
It is unclear what impact the technology could have on equine sports.

The Jockey Club, which regulates the thoroughbred horse racing industry,
strictly forbids in vitro fertilization and cloning. But sport
horses used for other disciplines, including Olympic show jumping, are
under no such restrictions.

The American Mule Racing Association does not restrict any kind of reproductive
technology.

“I hope one of these clones will be made available for racing,”
says Jacklin. “I see a whole revolution in terms of the way breeding
is done.”

Woods believes the horse research could have implications for human medicine.
Understanding how calcium is regulated in horse cells could help researchers
studying diseases like diabetes and prostate cancer, which involve high
calcium levels.

Furthermore, horses may be good models of diseases that occur late in
life because horses—unlike laboratory mice—can live for 30
years or more.

“The horse is a thousand-pound mouse that kicks,” Woods says.

Mule Racing?

Those
who follow the Triple Crown races every spring may not have noticed
that mule racing is taking off in many western states. “California
is the real mule racing hotbed,” says Don Jacklin, president
of the American Mule Racing Association. “Fans just love it.”

Approximately
70 mules race on the circuit. Mules tend to be better sprinters
than distance runners. They can run faster than Arabians and appaloosas,
but not as fast as quarterhorses and thoroughbreds.

A typical
day at the mule races starts with two or three races each run by
quarterhorses and thoroughbreds, and a mixed breed race. The same
jockeys that ride horses ride mules. Because there are so few competitors,
there is usually only one mule race, and often it is the featured
race at the end of the day.

But all
that could all change with the cloning of Idaho Gem. He is a genetic
brother of Taz, a world champion three-year-old and the circuit’s
runner-up for the last three years. The current world champion mule
racer is Black Ruby, a female mule.